1. Technical Field
The present invention relates generally to measurement systems for accurately measuring the amount of particulate pollutants within the exhaust gas stream of an engine, and more particularly to a measurement system which not only accurately measures the amount of particulate pollutants within the exhaust gas stream of an engine but which can also replicate engine exhaust stream characteristics under highway or roadway atmospheric conditions so as to additionally determine the size of the particulates which are prevalent within real atmospheric conditions.
2. Background Art
Exhaust emissions from motorized highway vehicles are currently regulated by the Federal Government and therefore must not exceed predetermined contaminant levels as set forth, for example, within Title 40, Chapter 1 of the Code of Federal Regulations, Section 86, Subpart C. As a result of these regulations, increasingly more sophisticated testing equipment has been developed to test and analyze engines for conformance with such standards. For example, one regulation established by the Environmental Protection Agency (EPA) sets a particulate limit standard of 0.60 g/hph for diesel truck engines wherein the particulates are defined as matter. Such matter being agglomerated carbon particles absorbed hydrocarbons, and sulphates. Condensed water which is not considered matter can be collected on a special filter after dilution of the exhaust gas stream by ambient air to a maximum temperature level of 52 degrees C. or 125 degrees F.
In order to obtain consistent or reliable results, it is mandatory that the fluidic addition of the dilution air be accomplished at accurately controlled flow rates which may nevertheless be varied within predetermined ranges depending upon the operating temperature and pressure levels or parameters. A system for achieving such a goal has in fact been previously developed by the present inventor and is disclosed within U.S. Pat. No. 5,058,440 which issued on Oct. 22, 1991.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the invention a sampling system has a plurality of diluters arranged in a serial array along an axial extent; a source of gas fluidically connected to the plurality of serially arranged diluters so as to supply a gas stream into each one of the plurality of serially arranged diluters in a serial manner; a source of dilution air fluidically connected to each one of the plurality of serially arranged diluters so as to supply dilution air into each one of the plurality of serially arranged diluters such that the dilution air is supplied into the gas stream present within each one of the plurality of serially arranged diluters so as to progressively dilute the gas stream as the gas stream flows through the plurality of serially arranged diluters; and sampling apparatus fluidically connected to each one of the plurality of serially arranged diluters for obtaining the analyzing a sample of the diluted gas stream present within each one of the plurality of serially arranged diluters.